Rock-drill.



l No. 874,455.

' PATENTED DEC. 24, 1907. P. V. W. SWANI'0N.& B., PRICE.

RoGKlDR'ILL. Y

PPLIdnIox FILED 1111.112. 1901.

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No. 874,455. I RATRNTRD DRG. 24, 1907.

RV. W. SWANTON R R. PRIGR.

' ROCK DRILL.

APPLIOATION FILED JULY 12. 190.7.

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UNiTED' sfrArlEs rnrinr oFFioE.

FREDERICK VICTOR. WILLIAM SWANTON AND BURT PRICE, OF BRAAMFONTAIN,

JOHANNESBURG, TRANSVAAL.

ROCK-DRELL. d

Specicaton of Letters Patent'.

Fatented Dec. 24, 1907.

Application filed July 12. 1907 Serial No. 383.545-

To all 'whom it lmay concern.

jects of the King of (.rreat Britain, and resil required, the faces are bellied out and vice Braainl'ontain, Johannesburg, and 112 de dents, respectively, of 48 Juta street,

Korte street, raanifontain, Johannesburg. l

Transvaal, have invented a new and useful lm rovement in .Rock-Drills, of which the fol owing is a specification.

'lliis invention relates to improvements in rock-drills of that class comprising a stock and a pluralit of cutting elements removably secured t ereto.

'lhe invention has to do with a drill of this character and more particularly with an imroved means for facilitating the removable ocking of the cutting elements in the stock, its further object being to secure said elements in a manner to permit ready removal f thereof and to provide and secure an ell'ectreception of the cutting bits g, h, and theV `another ciD the cutting live anchorage. 4

rlhe inventlon 1s illust-rated 1n the accom.

panying d; `iwings in which Figure l is an end view of a rock drill enibodying the main features of my invention, and Fig. 2 a side view, partly sectional, of a star drill enibodyin the invention, F ig. 3 shows the pressure p ates hereinafter described, Fig. 4 is a perspective view of one of thecuttinfr elements', F10. 5 a similar view ofelements, `Fig. 6 is an end view of a modification of the invention, Fig. 7 is a section on the line A--A Fig. 6, the cutting elements beiner removed, Fig. 8 is an enlarged elevation wii the cutting elements in position and Fig. 9 shows one o the cutting elements adapted for the second modification. 4 d

Referring to Figs. 1 to 5, a indicates the shank of the drill, which is screw-threaded at b and terminates in a cylindrical spigot c.

d is a separable bit stock which is tapered externally similarly to the head of solid drills and is made polygonal at e to receive a spanner. It is internal] threaded to fit on to the threaded portion of the shank and has above the threaded portion a central hole through which the spiglpt c may pass snugly. v

In .the face of the stoc are formed, at right angles to one another and intersecting at the axis, the undercut or dovetail slots f for the pressure plates i. Bits of triangular section are employed, thesection being preferably also equilateral-in order that the severalI edges may be used in turn for cutting. In the iigurethey are shown with llat faces, but Where more obtuse andstronger edges are versa to produce more acute cutting edges the faces are made concave. (lne long bit g, and two short bits l1 are provided; the former being long enough to extend slightly beyond the stock d at each side and the latter of such length as to touch the long bit at the center-and project corres iondingly beyond the stock. 'lhe edges of tlie long bit are cut away centrally to form recesses into which the short bits lock as seen in Fig. 1; the object heilig to prevent lateral movement ol" the long bit, which, striking the rock as it does equally at either extremity, is liable to such displacement, whereas the short bit-s, on the other hand, tend to move inwardly only under the iniiuence of the blows upon their outer extremities. The absence of cutting edges at the center of the tool also is found to increase the .efficiency of the drill; and it moreover permits the introduction of Water to the bore-hole through the shank, which may be made hollow for this purpose. Under the bits in each slot are inserted the pressure plates i, which are moved-out centrally at k' to permit oi'etlieir yin(r in the same plane.

are initially curved upwardly as seen in In preparing the drill for use the pressure plates 'i areput into the bottom of the slotsf, the long bit g is slid into place and the short bits h are thrust into their slot from each side to engage with the recesses j in the long bit g. The stock d is then screwed down on to the shank a., whereby pressure is ap lied by thev s igot c to the intersection of t e pressure p ates i and transmitted by them, 1n conse# quence of theirinitial curvature, overthe greater part of the base area of all the bits. The latter are thus forced land securely held between the pressure plates i and the overhanging edges ofthe dovetail slots f.

After the protruding edges of the bits have become worn down-'by use, the bits are with- ,ized for three further drillings .by turning them end for endl in the stock.

In the modification illustrated in Fi a6 to l l9 short b its l only are employed, in t is ini stance three in number, though more or less may be used, and such bits are moreover all of similar form. They are so disposedas to slope in towards the center, which arrangement facilitates breaking the rock and obviates outward displacement of the bits. The pressure plates are dispensed with, ressure i eing appllied directly to the bits by the spigot c t e upper surface of which is dished as shown in continuation of the sloping boti toms of the dovetail slots f. The spi ot c is continued as a conical nose m to ador abutment for the inner end of the bits, which nose l may in some cases be made detachable to en- 3 able it to be replaced when worn.

What l claim is l l. in a rock drill, a bit stool: having underi cut grooving cn the face, triangular cutting l means located in the grooved face and having an interlocking relation with each other and means for applying pressure to the underl side of such cutting means to lock the same 1 in position.

2. A. rock drill comprising in combination a shank, a bit stock movable longitudinally thereuponand having undercut grooving on the face, triangular cutting means located in l the grooved face and having an interlocking relation witheach other and means operatin upon relative movement oi shank and stoc to apply pressure to the .underside ci the cutting means to lock thesame in position.

3. A rock drill com rising in combination a threaded shank, a it stock threaded to screw thereon, said stock havin undercut grooving in the face, triangular its fitting therein and so disposed as to be engaged by recesses for locking with the short bits, z silient pressure plates under the bits adapted avance triangular bits fitting therein, pressure plates under the bits, said plates being adapted to be engaged by theextremity of the shank and to distribute the pressure therefrom f evenly over the bits.

5. A star rock drillcomprising a threaded shank, a bit stock screwed thereon and having two intersecting undercut Grooves formed in the face, short trianguiar bits located in one such groove, a long trianguiar bit located in the other groove and having to be engaged by the extremity of the shank and being initiallyr curved so as to distribute lie pressure from 'the shank' evenly over the its.

6. A rock drill comprising incombination, a bit stock provided with under cut grooving, cuttersof angular cross section seating in said lgrooving, and a shank engaging the bases oi" said cutters with one of its ends and mechanically lconnected with said stock whereby' relative movement of the stock and shank serves to force said cutters into engagement with said groovin ln testimony W ereoi we aiix our signature in presence of two witnesses.

. FREDERICK VICTOR WlfllvAll SWANTON.

BUR'I PRICE.l

Witnesses 2 ALFRED L. Sroon,

WM. D. GORDON. 

